MICROSTRUCTURE AND MAGNETIC PROPERTY OF FE-AL2O3 GRANULAR FILMS

Granular magnetic films composed of randomly or highly oriented Fe nan oparticles covered with amorphous Al2O3 have been synthesized by elect ron beam deposition. The highly oriented Fe nanocrystals are prepared by taking advantage of the epitaxial growth of alpha-Fe on <100> orien ted Au ''seed'' nanoparticles, which are epitaxially grown on a (100) NaCl substrate. The magnetic coercivity of the granular films with ran domly oriented Fe nanocrystals is inversely proportional to the interg ranular distance. For the film with an average Fe thickness of about 3 nm, the coercivity and the electrical resistivity are 944 Aim and 154 000 mu Omega cm, respectively. Coercivity of highly oriented granular films with similar average Fe thickness is generally one order higher than that of granular films with randomly oriented Fe particles. It is shown that the size, intergranular distance and crystalline orientati on can be controlled by epitaxial growth on ''seed'' particles. (C) 19 98 Acta Metallurgica Inc.